Hello! I hope someone can help me solve this problem.
I tried to open my task Manager to stop some of running programs, I press Ctrl-Alt-Del as usual, the Task Manager didn't display. It alwasy working fine before, I don't know what cause it stop working, can anyone help me solve this problem please!
Thank you so much!

Can you right click the Task Bar & open the Task Manager?

Can you open it from the Start Menu: Start/Run/ taskmgr?

This behavior can be caused by a virus. One of three:

W32.Spybot.Worm
http://securityresponse.symantec.com...ybot.worm.html

W32.Klez.Worm
http://securityresponse.symantec.com...klez.e@mm.html

W32.Yaha.Worm
http://securityresponse.symantec.com....fankr@mm.html

If the above isn't the case try:

Enable the Task Manager (Line 51 and 275)
http://www.kellys-korner-xp.com/xp_tweaks.htm

Lift Restrictions - Task Manager, Regedit and CMD (Line 275)
http://www.kellys-korner-xp.com/xp_tweaks.htm

Troubleshooting the Task Manager
http://www.kellys-korner-xp.com/xp_t.htm#tm

Emergency Msconfig, Regedit, Task Manager
http://www.dougknox.com/xp/utils/xp_emergencyutil.zip